Supersensitive impact sensor



April 8, 1969 Q E HART ET AL 3,437,041

' SUPEHSENSITIVE IMPACT SENSOR Filed May 29, 1967 LIGHT SOURCE Fl (3. I.

INONROTATING TUBE 57 SCR FIG. 2

INVENTOR OTHO E. HART SAMU E 1. A. MILLE R BY MULLER ROY MILLER OR N E Y United States Patent Ofiice 3,437,Ml Patented Apr. 8, 1969 US. Cl. 10270.2 5 Claims ABSTRACT OF THE DISCLOSURE Impact fuze for ordnance devices which initiates a detonator upon interruption of the light beam of a photovoltaic cell.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to improvements in sensitive impact fuzes which initiate a detonator at the surface of either a hard of soft target.

Certain fuzes heretofore devised, if designed for operation against a hard target, such as the ground, have not been entirely satisfactory against soft targets, such as snow, marshes, water, and the like, since excessive penetration into the soft medium occurred before detonation, thus materially reducing or nullifying the desired explosive efl ects. While certain fuzes such as VT or proximity fuzes have been devised which initiate a detonator adjacent the surface of any target, either hard or soft, they are costly, standoff distance is variable and they will not penetrate dense foliage before initiation.

One of the objects of the invention is to provide a fuze which initiates a detonator upon impact with hard or soft targets.

Another object is to provide a fuze initiator with the capability of penetrating foliage and the like without initiating a detonator.

A further object is to provide a fuze initiator which is simple in construction and economical of manufacture.

Still further objects, advantages and salient features will become apparent from the description to follow, the appended claims and the accompanying drawings, in which:

FIG. 1 is a cross section, partly diagrammatic, of the environment of the invention in a missile, and

FIG. 2 is a circuit diagram.

Referring now to the drawing, and first to FIG. 1, the forward end or ogive of a missile is provided with mounting member 12 immovably afiixed to the missile, and a slideable tube 14, urged to the position shown by a spring 16. A light source 18 and a photo-voltaic cell 20 are also immovably affixed to the missile and the tube is provided with a pair of aligned apertures 22, 22 through which a beam of light from the light source may pass to impinge on the photo-voltaic cell. As will be apparent, if the front end of the tube impacts a hard target such as the ground, it will be forced rearwardly against the urge of the spring, interrupting the beam of light and if it impacts a soft target, such as snow or water, the soft media will be rammed into the tube, also interrupting the beam of light. Thus, regardless of the hardness of the target, the beam of light will be interrupted substantially at the surface of the target media.

Referring now to FIG. 2, the light beam, photocell and apertured tube, just described, are associated with a circuit including a switch, illustrated as a silicon controlled rectifier (SCR), which, when in conducting condition, permits current to pass through the bridge wire of a detonator D.

In the operation of the circuit, switch S is first closed by a sequencing or timing device T and the 3 v. power source causes the light to project a beam onto the photovoltaic cell. The photo-voltaic cell now applies a negative bias to the gate of the SCR holding the SCR in a nonconductive state. Switch S is next closed by the sequencing device, establishing a circuit with the 6 v. power supply to the gate of the SCR through resistor R. The voltage at the gate is now at the proper value to maintain it closed when the arming switch S is next closed by the sequencing device but insufficient to maintain it closed in the absence of the photocell voltage. Thus, as will be apparent, when the light beam is interrupted, current flows through the bridge wire of the detonator.

In the device so far described tube 14 is axially movable relative to the transverse light beam when the missile impacts a hard target. In an alternative form of the invention the tube may be immovable and the light source located in a position on the missile such that it is destroyed upon impact, thus interrupting the light beam. Since movement of the tube is not necessary when it penetrates a soft target, the operation is the same as previously described.

What is claimed is:

1. A missile fuze, for use in a missile, for initiating a detonator upon impact of the missile with a soft media, comprising:

(a) a tube disposed at the forward end of the missile having a forward open end adapted to penetrate into the media and force it into the bore of the tube.

(b) said tube having a pair of transversely aligned apertures,

(c) a photo-voltaic cell and a light source disposed in a position to project a beam of light across the tube, through the apertures, and onto the photo-voltaic cell,

(d) a circuit including said photo-voltaic cell and an electrically initiated detonator, connected with a switch adapted to be closed when media enters the tube and interrupts the light beam.

2. Apparatus in accordance with claim 1 wherein said tube and light beam are relatively movable and adapted to interrupt the light beam upon impact with a hard target.

3. Apparatus in accordance with claim 1 wherein said switch is of a type having a gate adapted to close a circuit through the detonator in response to change of gate voltage applied by the photo-voltaic cell.

4. Apparatus in accordance with claim 3 wherein the switch is a silicon controlled rectifier.

5. Apparatus in accordance with claim 4 including a sequencing device adapted to close a circuit to the gate to provide a gate holding voltage and thence close an arming circuit to the detonator.

References Cited UNITED STATES PATENTS 2,060,206 11/1936 Hammond 102-762 2,927,213 3/1960 Marion et al 10270.2 X 3,228,337 1/1966 Grantham et al 102-702 VERLIN R. PENDEGRASS, Primary Examiner. 

